Is there a benefit in bonding amalgam restorations to remaining tooth structure Essay Example for Free

Is there a benefit in bonding amalgam restorations to remaining tooth structure Essay The use of bonded amalgam in restoring the teeth began as early as the 1990’s when a few practitioners began to use certain substances to bond the amalgam restorations directly to the tooth. These practitioners began to bond the amalgam directly to the enamel and/or the dentin. The process of bonding amalgam to the tooth was fairly simple. First, the cavity was prepared and the surface of the cavity was thoroughly cleansed, washed and dried. An etchant was applied to the surface of the cavity, and etching was done for certain period of time. Then, a bonding agent was applied to the surface of the prepared cavity. This bonding agent was chemically cured. After this, amalgam can be condensed into the cavity. The resin can whilst curing, bond the magma to the tooth. A mechanical interlocking between the amalgam and the resin would develop. Such restorations would have a lot of advantages over conventional amalgam restorations. However, the evidence available currently regarding bonded amalgam is rather insufficient, as the results of long-term studies are lacking. Studies for a period of two years following the insertion of bonded amalgam have been conducted, and benefits predicted on a long-term basis needs to be thoroughly tested (Bryant, 1998). The use of bonding agent for dental amalgam was first thought of immediately after composite resins were successfully bonded clinically. One of the most frequently utilized agents for bonding amalgam to the tooth structure is 4-META. This enables bond shear strength of about 10 MPa. On the other hand, if the same agent is utilized to bond composite resins to the tooth structure, a bond strength of about 20 MPa is achieved (Graig, 2002). One of the main reasons why dental researchers began to work on the use of bonded amalgams for clinical use was because the newer restorative material have not been very successful in replacing dental amalgam. During the early days when bonded amalgams were initially tested, researchers were able to notice that bonding helped to provide certain benefits against unbonded amalgams (Zbynek, 2002). Bonded amalgam restorations claim several benefits:- 1. The retention form of a cavity may be improved following use of bonded amalgam (Bryant, 1998). However, some researchers feel that the bond retention offered by bonding amalgam be very less or even negligible. This is because the bonding agent may not adopt in a proper manner to the surface of the cavity or the amalgam (Graig, 2002). 2. There is no much of need to cut the tooth extensively and to prepare several retentive features such as grooves, dove tails, undercuts, etc. 3. As the tooth is prepared conservatively, the resistance form of the tooth is improved. This means that the restoration can tolerate stresses better that could fracture the cusps. The clinical evidence available for this in the form of clinical trials is rather insufficient in this regard (Bryant, 1998). Studies have shown that in a MOD (class VI) cavity prepared with amalgam, the resistance to fracture was more than doubled when a bonding agent was utilized, compared to in situations when a bonding agent was not utilized. The case of the improvement in the facture strengths of bonded amalgam was comparable to that of bonding composite resins. The fracture strength achieved by bonding composites was similar to that of bonding amalgam in case of MOD restorations. However, in both cases, the resistance to fracture was as not as high as that of normal tooth material. The fracture resistance depended on several factors such as the amount of tooth material cut, the width of the proximal box, etc. Studies have shown that as the width of the restoration is increased, the resistance to fracture decreases. Research has also demonstrated that the retention obtained by bonding amalgam for MOD cavities was similar to that of placing pin-retained restorations. Hence, the potential to use bonded amalgam instead of pin-retained restorations could be considered. However, long-term studies in this regard have not been considered (Graig, 2002). Some other situations in which bonded amalgam restorations could be useful include large cavity preparations in posterior teeth (as the extent of the cavity preparation would reduce) and in class V cavities in which the occluso-gingival height is reduced, as the need for pins is eliminated (Zbynek, 2002). 4. As the tooth is cut to a conservative extent, and the need to build several retentive features is reduced, the chances of the patient developing post-operative hypersensitivity are greatly reduced. Besides, the resin bonding agent tends to seal the dentinal tubules and prevent the excessive drying (Zbynek, 2002). However, several other factors plays a very important role in preventing the development of hypersensitivity including the extent to which the amalgam is condensed, excessive drying of the tooth, the experience and the technique utilized by the dental practitioner, etc (Bryant, 1998). 5. Bonding agents help to improve the marginal seal and reduce the microleakage in a dental amalgam restoration. The gap present between the tooth and the amalgam is reduced thus lowering the microleakage (Zbynek, 2002). The fluid flow into the cavity is either abolished to decreased (Graig, 2002). Besides, the dentinal tubules are sealed to a greater extent, which could reduce and prevent damage to the pulp (Bryant, 1998). The microleakage is frequently measured using the dye leakage technique (Cenci, 2004). 6. The bonding strength between the tooth surface and the restoration is increased when an amalgam bonding agent is utilized. Studies have shown that the bond strength that develops when no bonding agent is utilized is about 4 to 8 MPa. However, when a bonding agent is utilized, the bond strength shoots up to about 20 MPa (Graig, 2002). 7. The rate of secondary caries is reduced (due to better marginal integrity and reduced marginal leakage) (Zbynek, 2002).